Role of Intraoperative Neuromonitoring to Identify External Branch of Superior Laryngeal Nerve During Thyroidectomy.

To evaluate the role of Intraoperative neuromonitoring (IONM) in visual and functional identification of external branch of superior laryngeal nerve (EBSLN) during thyroidectomy operation, 2. To identify the anatomical variations of EBSLN according to Cernea classification. This is a prospective observational study done on 30 patients who underwent thyroidectomy operation at the Department of Otorhinolaryngology in a tertiary medical institute. EBSLN was visually located and identified which was then confirmed by IONM. Identified nerves were classified according to Cernea classification. Results: Out of 34 EBSLNs, a total of 30 (88.2%) nerves were identified. Visual identification was successful in 19 (55.9%) nerves and 28 (82.4%) EBSLNs were functionally confirmed by IONM. Additionally, 11 (32.4%) branches were identified only by IONM which was statistically significant ( = 0.0135). IONM failed to confirm 2 visually identified nerves. Cernea type 2a was found to be the commonest EBSLN branching type (44.1.%) followed by type 1 (29.4%) and type 2b (14.7%). As visual identification and exposure of the EBSLN do not always ensure the motor integrity of the nerve, IONM has proved to be an important tool to identify and confirm functionality of the nerve during thyroidectomy operation. Cernea type 2a being the commonest presentation, we should direct our dissection more carefully in the region within 1 cm above the upper pole of the thyroid.